1. Field of the Invention
This invention relates to measurement and data acquisition systems and, more particularly, to isolated data acquisition applications.
2. Description of the Related Art
In isolated data acquisition (DAQ) applications, DAQ boards typically need to provide a high level of I/O connections which perform some kind of measurement and are electrically isolated from the host bus. In other words, a bank of measurement devices or subsystems may be isolated from a computer bus, such as USB or PCI. Each subsystem may operate asynchronously with respect to the other subsystems. Also, each subsystem may need to keep constant communication with the host system either to receive or generate data, as well as to generate status or events of interest to the user.
In typical DAQ systems, these requirements may be met by isolating the measurements at the I/O. However, there are several drawbacks to isolating the measurements at or near the I/O. First, since DAQ boards typically have numerous I/O lines, isolating the measurements at or near the I/O typically requires a large number of isolator devices. This increases the cost of the DAQ board, increases the power consumption, and reduces the area in the board that is available for circuit implementation. Second, an isolated DAQ has lower performance compared to a non-isolated device, because low-cost isolators are usually slow and fast isolators typically introduce skew and jitter between the lines being isolated. Lastly, from a practical sense, it is usually discouraged to interface high-resolution data converters with a parallel interface.
Many other problems and disadvantages of the prior art will become apparent to one skilled in the art after comparing such prior art with the present invention as described herein.